1. Field of the Invention
The present invention relates to a method of manufacturing a thin-film magnetic head.
2. Related Background Art
When manufacturing a thin-film magnetic head, its upper magnetic pole has conventionally been formed into a narrow pattern by ion milling. When ion milling is used, however, a region under the erect upper magnetic pole may attain a raised form whose apex is located near the magnetic pole, thereby causing so-called ATE (Adjusting Track Erase), which unintentionally erases data.
Therefore, a technique of narrowing the upper magnetic pole by reactive ion etching (RIE) instead of ion milling has been proposed. This technique will be explained with reference to FIGS. 17 and 18. FIG. 17 is a view showing a step in a conventional process of manufacturing a thin-film magnetic head, whereas FIG. 18 is a view showing a step subsequent thereto.
First, as shown in FIG. 17, a lower magnetic pole layer 101, a gap layer 102 made of a nonmagnetic material, a first upper magnetic pole layer 103, a second upper magnetic pole layer 104, and an insulating layer 105 made of alumina or the like are formed in this order. Subsequently, a narrow mask 106 is formed on the insulating layer 105 by plating or the like.
Next, as shown in FIG. 18, the insulating layer 105, second upper magnetic pole layer 104, and first upper magnetic pole layer 103 are patterned by RIE in conformity to the form of the mask 106. This drawing shows the state in the middle of etching, in which side walls of the first upper magnetic pole layer 103 are not vertical. The etching will advance further from the depicted state in order to make the side walls of the upper first magnetic pole layer 103 vertical.